How Does Blood Pressure Vary Between Arteries and Veins

Blood pressure varies dramatically between arteries and veins. This pressure gradient is what drives blood flow through the entire circulatory system, moving from an area of high pressure to an area of low pressure.

• Arteries (and Arterioles):
  • Experience high pressure because they directly receive blood pumped from the heart's powerful left ventricle.
  • The pressure is pulsatile, meaning it fluctuates between a high point (systolic pressure, e.g., 120 mmHg) when the heart beats, and a low point (diastolic pressure, e.g., 80 mmHg) when the heart rests.
  • This high pressure is necessary to push blood through the billions of tiny capillaries in the body.
• Veins (and Venules):
  • Experience very low pressure. By the time blood has passed through the capillaries and entered the venules and veins, most of the pressure from the heart's pump has been lost to friction.
  • Venous pressure is typically very low (e.g., around 10 mmHg in venules, dropping to near 0 mmHg by the time it reaches the right atrium of the heart).
  • This low pressure is why veins rely on valves and the skeletal-muscle pump to return blood to the heart, as pressure alone is insufficient, especially against gravity.